1. Field of the Invention
This invention relates to a data sorting apparatus utilized in a CAD system, a game machine or the like using three-dimensional graphics or the like, and more particularly to a sorting apparatus capable of inputting and outputting base axis data of three-dimensional images in synchronism with a video rate (a frame switching rate).
2. Description of the Related Art
JP-A-2-224018 describes a prior art method relating to an apparatus for sorting base axis data of three-dimensional images. According to this method, for the purpose of sorting a plurality of data at high speed, a base axis data memory, a data number pointer, a first buffer memory, a last buffer memory, a chain buffer memory and a sorting control circuit for controlling data writing and reading in and from the individual memories are provided. Data transfer operation is repeated twice, that is, data transfer of inputted base axis data to the first buffer memory, the last buffer memory and the chain buffer memory and data transfer from the first buffer memory and the last buffer memory to the chain buffer memory are repeated for sorting the base axis data, so that the number of times of data transfer can be decreased, and the data sorting can be carried out at high speed.
In the case of the prior art sorting method, it has been difficult to sort a large quantity of base axis data at the video rate. That is, according to the prior art sorting method, the desired sorting cannot be executed until all the base axis data are inputted. Also, the sorted base axis data cannot be outputted until sorting of all the data is completed. Therefore, even in the case of sorting a train of base axis data supplied as an input; three phases: a first phase of inputting the base axis data; a second phase of sorting the base axis data and a third phase of outputting the sorted base axis data in the sorted order have been required, and a considerable period of time is consumed until the base axis data are outputted in the sorted order after all the base axis data are inputted.
An apparatus capable of realtime sorting of base axis data in conformity with the rate of supplying the base axis data as its input has been considered. However, since the scale of such an apparatus tends to become large due to, for example, the requirement for a large number of memories, it is considerably difficult to put such an apparatus into practical use when the number of base axis data to be sorted is quite large.